A girl runs up the down escalator in the mall. If the escalator is moving with a velocity of 24 m/min and the girl is running with a velocity of 30 m/min, how far up the escalator can she go in 4 minutes?

A. 10 m
B. 30 m
C. 48 m
D. 24 m

D. 24 m

Explanation:

Running up - velocity     + 30 m/min

Escalator 's moving down  velocity   - 24 m/min

Sum velocity (30 - 24) = 6 m/min

6 m/min * 4 min = 24 m

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.